Bacterial infectious diseases kill 100,000 persons each year in the US and 11 million persons each year worldwide, representing nearly a fifth of deaths each year worldwide (Heron et al., Final Data for 2006. National Vital Statistics Reports, Vol. 57 (Centers for Disease Control and Prevention, Atlanta Ga.) and World Health Organization (2008) The Global Burden of Disease: 2004 Update (World Health Organization, Geneva)). In the US, hospital-acquired bacterial infections strike 2 million persons each year, resulting in 90,000 deaths and an estimated $30 billion in medical costs (Klevins et al., (2007) Estimating health care-associated infections and deaths in U.S. hospitals. Public Health Reports, 122, 160-166; Scott, R. (2009) The direct medical costs of healthcare-associated infections in U.S. hospitals and benefits of prevention (Centers for Disease Control and Prevention, Atlanta Ga.)). Worldwide, the bacterial infectious disease tuberculosis kills nearly 2 million persons each year. One third of the world's population currently is infected with tuberculosis, and the World Health Organization projects that there will be nearly 1 billion new infections by 2020, 200 million of which will result in serious illness, and 35 million of which will result in death.
For six decades, antibiotics have been a bulwark against bacterial infectious diseases. This bulwark is failing due to the appearance of resistant bacterial strains. For all major bacterial pathogens, strains resistant to at least one current antibiotic have arisen. For several bacterial pathogens, including tuberculosis, strains resistant to all current antibiotics have arisen.
Bacterial RNA polymerase (RNAP) is a target for antibacterial therapy (Darst, S. (2004) Trends Biochem. Sci. 29, 159-162; Chopra, I. (2007) Curr. Opin. Investig. Drugs 8, 600-607; Villain-Guillot, P., Bastide, L., Gualtieri, M. & Leonetti, J. (2007) Drug Discov. Today 12, 200-208; Ho, M., Hudson, B., Das, K., Arnold, E., Ebright, R. (2009) Curr. Opin. Struct. Biol. 19, 715-723; and Srivastava et al. (2011) Curr. Opin. Microbiol. 14, 532-543). The suitability of bacterial RNAP as a target for antibacterial therapy follows from the fact that bacterial RNAP is an essential enzyme (permitting efficacy), the fact that bacterial RNAP subunit sequences are highly conserved (permitting broad-spectrum activity), and the fact that bacterial RNAP-subunit sequences are not highly conserved in human RNAP I, RNAP II, and RNAP III (permitting therapeutic selectivity).
Accordingly, new antibacterial agents are needed.